A cash advance is a short-term loan that is designed to cover important needs and then be repaid via upcoming income. If that makes you think, "Wait, this sounds just like a payday loan," then you are partially right: The two loans are similar and the names are often used interchangeably. However, a cash advance does have some small but important differences.
While a payday loan typically depends on one thing – your next paycheck – a cash advance loan tends to be more flexible. It is also often based on credit cards or existing lines of credit, and frequently offered credit card companies that you may already use. This makes the process very easy: Essentially, you are using your current credit card to buy cash instead of products. That means, among other things, that your repayment terms will probably be quite similar to the terms you already have on your credit card.
A payday loan is useful for those who may have bad credit but have a very stable income that lenders can count on. A cash advance through a credit card or line of credit is useful for those who may not have such stable income, but have a very good credit payment history and represent relatively low risk for credit companies. Both, however, often work as a short-term solution to a sudden cash deficit where you need money now to cover necessary expenses.